1. Field of the Invention
This invention relates to a device for taking up a strip-like member such as a film onto a take-up shaft such as a reel.
The device of this type is used, for example, to take up microfilm wound on a reel onto another reel (a take-up device) to thereby move the frames of the film between the two reels and select a desired frame.
2. Related Background Art
The techniques described, for example, in Japanese Utility Model Publication No. 3491/1967, Japanese Laid-Open Patent Application No. 63645/1983, Japanese Laid-Open Patent Application No. 63646/1983 and Japanese Laid-Open Patent Application No. 153744/1984 are known as conventional strip-like member take-up devices. These are of a construction in which guide rollers having rotary shafts parallel to a take-up shaft are disposed around the take-up shaft and cause the take-up shaft to take up the leading end of a strip-like member such as a film. A typical example thereof will hereinafter be described with reference to FIGS. 18 and 19 of the accompanying drawings. In these figures, the reference numeral 1 designates a take-up shaft having attached thereto flange plates 1A and 1A substantially parallel to the width of a film. The flange plates are provided with pawls 1B and 1B inwardly protruding to resiliently hold the edges of the film therebetween. Guide rollers 10 and 11 mounted on arms 8 and 9, respectively, pivotable about shafts 8A and 9A, respectively, are in contact with the take-up shaft 1 to hold the film F between them and the take-up shaft 1, and the pawls 1B and 1B resiliently hold the edges of the film F being taken up and cause the film F to be wound onto the take-up shaft. As the amount of take-up increases, the arms 8 and 9 may pivotally move to thereby move the guide rollers 10 and 11. This device is constructed compactly, but since guiding is done only at the points of contact between the guide rollers and the take-up shaft, there has been the undesirable possibility of the film flying out in the direction of arrow C in FIG. 18.
Another example of the prior art is shown in FIG. 20 of the accompanying drawings In the figure, the reference numeral 1 denotes a take-up shaft having attached thereto flange plates 1A and 1A substantially parallel to the width of a film. The flange plates are provided with pawls 1B and 1B inwardly protruding to resiliently hold the edges of the film therebetween. Accordingly, the film F fed between the flange plates by a guide plate 2 is held by and between the pawls 1B and 1B and is wound onto the take-up shaft 1 by means of a belt 7 passed over immovable pulleys 3, 4, 5, a movable pulley 6 and the take-up shaft 1. As the amount of take-up progresses, the movable pulley 6 moves to a position as indicated by dots-and-dash lines in FIG. 20. In such a device, there is no possibility that in the portion wherein the film F is held between the take-up shaft 1 and the belt 7, the leading end of the film separates from the take-up shaft 1 and flies out. However, the film introducing portion of the take-up shaft 1 is not in contact with the belt 7 and therefore, in this portion, the leading end of the film F may separate from the take-up shaft 1 and fly out. To prevent the film from flying out and ensure the film to twine around the take-up shaft, the pawls 1B and 1B become necessary, and since the spacing between the pawls 1B and 1B is invariable, the width of the film which permits take-up is limited. Even if said spacing is made variable, the film cannot be accurately held between the pawls unless said spacing is set within a very narrow dimension, and the mechanism therefor will become complicated.
Also in FIG. 20, as the amount of take-up progresses, the movable pulley 6 moves to the position as indicated by dots-and-dash lines. In such a device, the movable pulley moves rectilinearly and therefore, the device requires a large space.
Also in FIG. 20, one of the immovable pulleys 3, 4 and 5 has been connected to a drive source so as to be rotatively driven and the take-up shaft 1 is rotatively driven by the belt 7.
When the film F is to be taken up in such an example of the prior art, if slack occurs in the leading end F1 of the film as shown in FIG. 21 of the accompanying drawings when the take-up of the film F is about to enter the second round at the start of the take-up of the film F, the slack tends to increase gradually. Such slack leads to an undesirable result during take-up and therefore, a countermeasure has been taken to eliminate it. For example, there is a method in which film keep pawls are finely arranged on the take-up reel, but in this method, the relative speeds of the flange portion provided with the keep pawls and the film must be balanced delicately. There is also a method of detecting the film speed by an encoder connected to a pulley through a belt to thereby control the film speed, but according to this method, the slack during the take-up of the film is liable to occur in the belt drive and therefore, due to the slip between the belt and the film, it has been difficult to control the film speed accurately.